1. Field of the Invention
The invention relates to a digitizing screen apparatus and a drive means for presenting projectable images to said digitizing screen.
2. Description of the Prior Art
The patent literature discloses several attempts to digitize images. One early technique was to drive a patterned back drop with respect to a plurality of small apertures. The pattern seen through the front apertures changes as the back drop is moved. Schemes such as the foregoing are described in U.S. Pat. Nos. 1,114,267 and 1,172,360, among others.
A more recent technique is to project an image onto a patterned screen. The pattern may take the form of quilting or other repeating features. U.S. Patent references discussing this type of technique include, but are not necessarily limited to, U.S. Pat. Nos. 3,423,896; 2,507,975 and 3,740,631.
Other U.S. patents of possible interest include U.S. Pat. Nos. 1,837,894; 3,335,457; 3,237,331; 3,314,179; 3,329,475; 3,568,346; 3,686,781; 3,783,539 and 3,987,558.
In addition to the foregoing, other efforts have been made to produce digital-like displays. For example, digitized signs can be found in places such as Times Square, New York City. According to one embodiment, a field of light bulbs is controlled by an array of photocells each actuating a single bulb on the display screen through an amplifier circuit. Movies of shadow graphs and in some cases real shadows are cast upon the screen from a control room behind the sign. The images projected on the photocells appear in lights on the display screen over the street.
Other, less costly efforts have been made to digitize images on a more modest scale. One device marketed under the name Channel 2000 incorporated a plurality of lenses. Another device known as Channel 1 used a single diffusing sheet and an egg crate separator. Both products were designed to be placed over TV screens to create amusing patterns.